Comparison of Representative Wet and Dry Fire Suppressants to Retard Fire Propagation in Lithium-Ion Modules Initiated by Overcharge Abuse 2023-01-0520

Overcharging lithium-ion batteries is a failure mode that is observed if the battery management system (BMS) or battery charger fails to stop the charging process as intended. Overcharging can easily lead to thermal runaway in a battery. In this paper, nickel manganese cobalt (NMC) battery modules from the Chevrolet Bolt, lithium manganese oxide (LMO) battery modules from the Chevrolet Volt, and lithium iron phosphate (LFP) battery modules from a hybrid transit bus were overcharged. The battery abuse and emissions tests were designed to intentionally drive the three different battery chemistries into thermal runaway while measuring battery temperatures, battery voltages, gaseous emissions, and feedback from volatile organic compound (VOC) sensors. Overcharging a battery can cause lithium plating and other exothermic reactions that will lead to thermal runaway. During the testing, VOC sensors were used to determine what, if any, amount of forewarning they may provide in the event the battery enters thermal runaway. Additionally, three different fire suppressant agents were also used to judge whether one is more effective than the other in extinguishing the battery fires. The fire suppressants were engaged sixty seconds after thermal runaway was detected, and their effectiveness was judged by visually evaluating whether the fire was extinguished and remained extinguished. Data is analyzed to extract comparisons in peak thermal runaway temperatures, the amount of forewarning the battery may provide preceding thermal runaway as measured by the pre-thermal runaway temperatures and VOC sensors, and other qualitative metrics observed during the testing. The emissions collected during the overcharge testing are summarized for all the three chemistries and various suppressants.